Humans show considerable interindividual variation in susceptibility to
weight gain in response to overeating. The physiological basis of this
variation was investigated by measuring changes in energy storage and
expenditure in 16 nonobese volunteers who were fed 1000 kilocalories per
day in excess of weight-maintenance requirements for 8 weeks.
Two-thirds of the increases in total daily energy expenditure was due to
increased nonexercise activity thermogenesis (NEAT), which is associated
with fidgeting, maintenance of posture, and other physical activities of
daily life. Changes in NEAT accounted for the 10-FOLD DIFFERENCES IN FAT
STORAGE THAT OCCURRED !!! [caps and exclamation points mine].

Levine, J.A., Eberhardt, N.L., and Jensen, M.D. 1999. Role of nonexercise
activity      thermogenesis in resistance to fat gain in humans. Science
283(5399):212-214.

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[log in to unmask] (Liza May)